The present invention is a cutting tool holder for an insert used with a lathe or the like. More particularly, the present invention is directed to a tool holder which incorporates a fluid passageway to direct coolant to at least one critical zone of the insert.
In rotary cutting of metal work pieces such as on a lathe, or the like, the life of the cutting tool insert is an important factor in determining 1) the number of work pieces completed in a fixed time period, and 2) the cost of operating the machine. A determining factor in wear life of the insert is the effectiveness of the coolant in preventing the interface of the cutting tool insert and work piece from reaching elevated temperatures. A number of coolant systems have been devised in an attempt to remove heat from this interface and, thereby, extend tool life. The chief problem with most of these systems is that the delivery system is too far from the interface. This results in ingestion of air into the flow stream which significantly detracts from the cooling effectiveness of the fluid coolant. Further, the more distant the delivery point is from the interface, the lower the percentage of coolant that will actually contact the interface. These two factors detract from the overall efficiency of these cooling systems.
One patent attempts to remedy these problems by providing the insert with a passageway through which high pressure fluid is directed. This patent, U. S. Pat. No. 5,237,894 issued to Lindeke, can get fluid near the interface but, obviously, can not focus coolant fluid directly at the interface between the cutting edge and the work piece without compromising the integrity of the cutting edge. A second patent, U. S. Pat. No. 6,053,669 to Lagerberg, uses a porous material for the insert. This patent also cannot focus a stream of coolant fluid at the interface; in addition, the fluid can only ooze out of this porous material. A fluid stream is not possible due to the material itself offering resistance. In addition, while Lagerberg hopes to avoid the clogging of a passageway by contamination in the coolant fluid, the presence of sludge from bacteria, large particles and/or small chips, in the supply line will result in clogging of the system and blocking off of flow into the porous insert.
The tool holder with coolant system of the present invention overcomes these defects by using portions of the holder to channel the coolant and focus the delivery point(s) toward at least one critical zone of the cutting tool insert. These critical zones may include, for example, a first and a second cutting edge and a nose portion positioned between the two cutting edges. The coolant system can be designed to handle either high or low pressure fluid delivery. The tool holder of the present invention includes a tool holder body, the body having a recess formed therein; a cutting tool insert seated in the recess, the insert having at least one critical zone; a top plate at least partially overlying and securing the insert in the recess; means securing the top plate to the tool holder body; and coolant passageway means formed in at least one of the tool holder body and the top plate, the coolant passageway means being focused on at least one of three critical zones. In one embodiment, the critical zone is selected from the group consisting of a first cutting edge, a second cutting edge, and a nose positioned between the pair of cutting edges. Preferably, the coolant passageway means focuses coolant on each of the first cutting edge, the second cutting edge and the nose.
The coolant passageway means comprises open sided channels cut in one of said tool holder body and the top plate, the open side being closed by at least one of i) the other of the tool holder and the top plate and ii) the insert. In one embodiment, the means to retain the top plate on the tool holder body comprises some welded portions. In another embodiment, the tool holder body is configured with a dovetail slot while the top plate has a complementary dovetail configuration on its lateral edges. A recess in one lateral edge of the top plate receives a pin that is engaged in the tool holder body to prevent movement of the top plate. Other means of securing the top plate such as soldering, gluing, conventional threaded fasteners, etc., could also be used.
The cutting tool insert is retained in the tool holder body by a combination of the top plate overlapping one edge of the insert and a conventional tilt pin which extends through an opening in the insert. Both the axial rake angle (10xc2x0) and the radial rake angle (7xc2x0) are increased from conventional tool configurations increasing tool life. Alternatively, a screw (beveled headed, flat head, Torx(copyright) drive) could be used to secure the insert in the tool holder body.
Other features, advantages and characteristics of the present invention will become apparent after a reading of the following specification.